Treuffet Johanne, Kubarych Kevin J, Lambry Jean-Christophe, Pilet Eric, Masson Jean-Baptiste, Martin Jean-Louis, Vos Marten H, Joffre Manuel, Alexandrou Antigoni
Laboratoire d'Optique et Biosciences, Ecole Polytechnique, Centre National de la Recherche Scientifique and Institut National de la Santé et de la Recherche Médicale U696, 91128 Palaiseau, France.
Proc Natl Acad Sci U S A. 2007 Oct 2;104(40):15705-10. doi: 10.1073/pnas.0703279104. Epub 2007 Sep 25.
We have implemented the recently demonstrated technique of chirped-pulse upconversion of midinfrared femtosecond pulses into the visible in a visible pump-midinfrared probe experiment for high-resolution, high-sensitivity measurements over a broad spectral range. We have succeeded in time-resolving the CO ligand transfer process from the heme Fe to the neighboring Cu(B) atom in the bimetallic active site of mammalian cytochrome c oxidase, which was known to proceed in <1 ps, using the full CO vibrational signature of Fe-CO bond breaking and Cu(B)-CO bond formation. Our differential transmission results show a delayed onset of the appearance of the Cu(B)-bound species (200 fs), followed by a 450-fs exponential rise. Trajectories calculated by using molecular-dynamics simulations with a Morse potential for the Cu(B)-C interaction display a similar behavior. Both experimental and calculated data strongly suggest a ballistic contribution to the transfer process.
我们在可见泵浦-中红外探测实验中，采用了最近展示的将中红外飞秒脉冲啁啾脉冲上转换为可见光的技术，以在宽光谱范围内进行高分辨率、高灵敏度测量。我们成功地对哺乳动物细胞色素c氧化酶双金属活性位点中从血红素铁到相邻铜（B）原子的CO配体转移过程进行了时间分辨，已知该过程在<1皮秒内发生，利用了Fe-CO键断裂和Cu（B）-CO键形成的完整CO振动特征。我们的差分传输结果显示，与Cu（B）结合的物种出现延迟（200飞秒），随后是450飞秒的指数上升。使用具有Cu（B）-C相互作用的莫尔斯势的分子动力学模拟计算的轨迹显示出类似的行为。实验和计算数据都强烈表明转移过程存在弹道贡献。
